Piston



Sept. 7 1926. l l `1,599,224

' W. S. FISHER PIsToN Filed July 18 1923 2 Sheets-Sheet l Illu-aw Sept. 7 19726.

l w.. s. FISHER v PIsToNv K Filed July 18 1923 2 Sheets-Sheet 2 Wa /fer H156 er.

. skirt Patented Sept.v 7, 1926.

UNITED STATES PATENT OFFICE.

WALTER S. FISHER, OF TOLEDO, OHIO, .ASSIGNOB TO THE WILLYS-OVERLAND COM- PANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO.

PISTON.

Application led July 18, 1923. Serial No. 652,302.

The present invention relates to pistons, and has for its object to improve the construction of pistons ofthe split skirt type used in gas engines and the like, whereby to increase their eiiiciency and prolong their length of service.

Split skirt aluminum pistons employed in cast iron cylinders frequently cause piston slap after a considerable period of use.

Apparently the skirt of the piston rolls' inwardly somewhat under the influence of heat and pressure long continued, and takes a permanent set with a diameter less than that of the cylinder. A solid iron ring mounted within the piston at the lower endV of the skirt in such a way as to permit the skirt to expand with respect to the ring, thus tending to closeup the space left by the split in the skirt, will cure the trouble, because the solid iron ring will act as a reinforcement to prevent the rolling in or distortion of the skirt.

One object of my invention is to provide a new and improved method of applying such reinforcement tothe skirt of a split piston.

Another object is to provide a new and improved method for bringing the diameter of the lower portion of the split skirt to an accurate dimension readily and quickly, without extreme care in machining.

A further object is to provide new and improved means for practicing the method disclosed herein.

To these and other ends, the invention embodies dilerent novel features of construction and arrangement of parts, which will lbe more fully described and claimed hereinafter.

A disclosure constituting one embodiment of the invention, is illustrated in the accom-l panying drawings, in which:

Figure I is a vertical section of an engine cylinder containing a piston constructed in accordance with my invention.

Fig. II is afragmentary section of the lower end of the piston, with the reinforcing parts omitted. y

Fig. III is a sectional plan taken on line III-III of Fig; I. f

In maintaining a uniform diameter for l the piston, determined by the running clearance therefor, I provide what is, in etfect, a solid relnforcingring within the lower 'end of the split skirt. The ring is made ofthe same material as vthe cylinder walls,

which usually are of cast iron or steel, and therefore has the same co-eiiicient of expansion as the cylinderwalls. The slotted skirt of the aluminum alloy piston, having a greater co-eiicient of expansion than the ring, will tend to creep around the ring without becoming distorted and without varying the diameter of the piston. If the solid ring were omitted, the'slotted skirt would tend to close in or collapse, dueA to the thrust on the skirt of the piston in operation. In this way the piston skirt would. become distorted, tak and resulting in a reduced diameter, thus increasing the slap and permitting the passage of excessive quantities of oil to the combustion chamber. Furthermore, excessive wear on the. wrist pin and other parts would thus result, and the efciency of the engine be considerably decreased. By the use of the substantially solid lcast iron or steel ring, the expansive properties of which conform closely to those of the cylinder, the original shape and diameter of the piston is more accurately maintained and the ob jections pointed out above are avoided.

The method disclosed herein, by which the uniformly correct diameters of the pistons are obtained, and the means by which the piston skirt is reinforced and held against distortion, constitutes a marked iming 'a permanent set provement in piston construction and affords a practical and economical form of piston, tending to increase the efficiency of the'engine and therefore reducing the cost of operation.

In carrying out my improved invention, I employ a piston 10 constructed in any approved manner and including a split skirt portion 11, suitable piston rings 12, and wrist pin bores 13, all as shown in Fig. I, the piston being shown within a cylinder 14 which forms no part of the present invention. Openings 15 are provided-in the wall of the piston for rendering accessible the bolts for securing the connecting rod with the wrist pin (not shown).

The skirt 11 anay have one or more longitu.- dinally disposed slots 16 therein, being preferably constructed with one only, as shown. Near the bottom Iof the skirt is formed an annular groove 17, adapted to receive an eX- pansible ring 18, having its free ends beveled as indicated at 19 in Fig. IV. A recess 2O is formed in the skirt of the piston for the reception of a wedge 21, adapted to be driven between the beveled portions 19 of ythe ring to `eect the desired expansion of the skirt. Other suitable expanding means for the ring, adapted for rigid connection with the piston, may be employed, if desired. The wedge or expanding member, when forced inwardly between the ends of the split ring the desired amount, is di rectly connected with the piston, preferably by means of a rivet 22 or similar retaining member inserted in registering openings formed in thel wedge and piston after the parts are asembled. One of. said openings is indicated at 23 in Figs. II and V, which may be formed in the piston before the applicati-on of the expanding device thereto, if desired.

The present method involves the insertion of the expansible ring within the groove 17; the application to the ring of an expanding device, such as the wedge 21; the mounting and securing of the piston and expanding parts in a suitable holder or gauge, such. as 24, having the desired diameter or having suitable limiting. portions to determine the expansion of the piston; the application of pressure to the expandying wedge, as by means of the screw 25; the

forming of one or both of the openings for the reception of the retaining member 22.

ing member 21, in order to force the walls of the piston skirt into engagement with the inner wall of the holder 24, a suitable tool, such as a drill, is inserted through the opening 27 of the holder and rotated to form the registering openings in the piston andretaining ring. As before stated, the opening 23 may be form'ed previous to the'application of theretaining device, if desired. The rivet 22 or other suitable retaining member is then inserted and secured, to permanently hold the expanding member in position.

The screw 25, threaded through the extension 28 of the holder, is preferably provided with 'a relatively movable portion 29, adapted to seat upon the wedge 21 as shown in Fig. VII, the connection between the screw and member 29 being preferably in i securing the Wedge upon the pist-on.

lVhile the construction herein shown and described is well adapted to fulfill the objects of the invention, it is t0 be understood that changes in the form, proportions, arrangement of parts and details of construction shown, may be resorted to when found expedient, without departingl from the spirit of the invention as expressed in the claims.

I claim as my intention:

1. The method oy |dimensioning the skirtJ of a Split skirt piston havingA a groove formed internally therein, which comprises inserting a divided expansible ring Within the groove, forcing a wedge along the inner surface of the skirt between the ends of the ring-to obtain the desired expansion, thereafter forming registering openings in the wedge and piston and subsequently inserting a retaining member for the wedge formed to fit tightly ins-aid openings.

2. The method of dimensioning the skirts of split skirt pistons for internal combustion engines and the like, which comprises inserting an expansible ring within the pisp'iston without removing the latter from 4. A slotted `piston having a, groove 1,0'

said holder. formed internally therein,\' an expansible 3. A slotted piston, an expansible ring ring 'disposed ,Withinfthe groove,v a, wedge mounted within the piston, means acting to fitted to the inner wall 'of the piston and 5 hold the ring expanded therein, said means driven between the ends of the ring to exf comprising a wedge fitted toa. side wall of pand the same, and means directly connect- "l5 the piston and means djrectly-vaixing the ing the wedge with the piston. l j last .mentioned means non-adjustably to the In testimony whereof,I ax my signature. 

